The BT-H magnetos use a capacitor discharge system to produce a very high voltage spark.  It is fired electronically so there are no points to set, check or maintain.

We fit a larger coil in the Vincent version of the BT-H magneto so that the magneto starts sparking at below 200 engine rpm.   Normal kick start speed is around 320rpm.  If you have the  Grosset electric start conversion this spins at approximately 340rpm.

The total advance is over 30 degrees.  The figures quoted are approximate as we tend to fine tune the Vincent magnetos on assembly.  In tests the Vincent start easily and runs very well using a similar curve.

The MK2 version of the BT-H magneto for the Vincent twin introduced mid '07 has a modified characteristics  The advance curve is a little longer than the original MK1 and it starts sparking earlier. (MK2 Advance Curve.)

The advance curve is analogue so it is not programmable.  

The twin engine built from new spares from the VOC Spares Company has been tested on a dynamometer using a one of our magnetos.  A  good setting was found to be 34 degrees full advance.  This could be a good initial figure to start with for your own engine.

The advance/retard in our magnetos is done electronically so a fixed timing wheel is preferred.   If you do not have a fixed wheel you may fix the mechanical advance/retard mechanism in the fully advanced position. We are advised that you can get the following parts from the VOCSC to convert to a fixed wheel system.  (Parts List)

We can supply the magneto with fixed ignition   This gives you the easy, no extra cost option of using your existing mechanical advance/retard.  You still get the benefits of an equally strong spark on both cylinders.  (N.B. We recommend a fixed magneto pinion and electronic advance as this is far more reliable and consistent than a mechanical advance.)

The ignition backs off  1 or 2 degrees at about 7-8 thousand rpm. (Not applicable to most Vincents!) 

During fitting the magneto is fixed in the correct timing fully advanced position using a locating peg through the magneto body.  This simplifies the timing process.  The bottom rear magneto stud is replaced by a stainless cap head bolt.  The bolt, a long hexagon screwdriver  and the locating peg are in the kit.

The magneto flange is fitted with a proper "O" ring rather than a paper  gasket and the fixing holes are slotted to allow approximately 10 degrees of fine adjustment without removing the magneto.  (This fine adjustment may not be available on all engines because of differences in the crankcase castings.)

The Vincent twin arrangement requires two small coils to be fitted with the magneto.  These fit easily underneath the standard magneto cowling.  We can supply extended connections if you wish to  mount the coils in a different position.

All the magnetos bearings are sealed for a long life.  The electronics are encapsulated for a long trouble free existence.  There are no parts inside that you will need to service.   We spend a lot of time in our workshops setting up our magnetos to give you optimum performance.   If you take the magneto to bits it is unlikely that it will work properly again, if at all.  This is not the usual disclaimer, it is fact.

We have had instances where some filing was needed to fit the new magneto to original crankcases. "B's" and "C's" had sand cast crankcases and may have varied in thickness somewhat.  "D" cases were die cast.

If you are not sure of anything please email us or send us a letter. If you need to come and see us make an appointment first as we may just be out riding our bikes.